Thermoplastic recording

ABSTRACT

The disclosure relates to a process and apparatus for recording information on a dielectric thermoplastic material in the form of a ripple pattern. A layer of dielectric photoconductive material may be used to form an electrostatic latent image, which is transferred to the thermoplastic material to control the deformation of the thermoplastic material in image configuration.

United States Patent Lessman [54] THERMOPLASTIC RECORDING [72] Inventor: Gerhard Lessman, Evanston, Ill.

[73] Assignee: Bell 81 Howell Company, Chicago, 111. [22] Filed: May 19, 1960 [21] Appl. No.: 30,291

[52] U.S.Cl. ..96/l.1,355/9, 340/173 TP,

346/74 TP, 178/66 TP [51] Int. Cl. ..G03g 13/22, B4lm 5/20 [58] Field ofSeareh ..95/l.7; 250/65.1; 96/1,46,

96/l.l; 178/LMS, 5.4, 7.5 D, 6.6 TP; 179/1001 B; 88/24 C; 346/74, 74 ES, 74 P, 74 TP; 355/9;

[56] References Cited UNITED STATES PATENTS 1,891,780 12/1932 Rutherford ..79/100.1 B

2,391,451 12/1945 Fischer ...l78/75 D 2,843,084 12/1958 Hayford.. ..95/1.7 l,690,584 11/1928 ..88/24 C12 Jones [4 1 Apr. 4, 1972 Primary Examiner-Charles E. Van Horn Attorney-Raymond A. Andrew [57] ABSTRACT The disclosure relates to a process and apparatus for recording information on a dielectric thermoplastic material in the form of a ripple pattern. A layer of dielectric photoconductive material may be used to form an electrostatic latent image, which is transferred to the thermoplastic material to control the deformation of the thermoplastic material in image configuration.

19 Claims, 1 1 Drawing Figures Patented April 4, 1972 L Y 8 8 3,653,888

4 Sheets-Sheet 2 I 'IIL I 'IIII. I '11, I 'IIIII I r/II/ I will I III! INVENTOR. Gerhard Lessman Patented April 4, 1972 4 Sheets-Sheet (5' INVENTOR. Gerhard Lessman Pamited Apii-l ,1972

4 Sheets-Sheet 4.

INVENTOR.

Gerhard Less/nan 1 THERMOPLASTIC RECORDING This invention relates to a thermoplastic recording, and more particularly to relief image photography.

There is a recently introduced type of recording in which a transparent backing film carrying a thinner thermoplastic facing with a conductive layer therebetween is placed in a vacuum with an electron gun which directs electrons in an image or intelligence pattern onto the facing to form negative charges on the outer surface of the facing. The negative charges cause correspondingly positioned positive charges to be formed on the inner surface of the facing. The film with its facing and charges thereon is then heated to a temperature at which the facing softens, and, the oppositely disposed positive and negative charges on opposite sides of the facing are attracted toward one another to make the thermoplastic film grooved or dimpled where the charges are located. The facing then is cooled to resolidify the facing which then has the image pattern in the form of grooves permanently therein. Light projected from a grating through the resulting film is refracted by the grooves to pass through a second grating and form an image on a screen. The above system of recording has many applications but hitherto has had the drawback of requiring vacuum for the formation of the charges by the electron gun, and the utility thereof would be greatly increased by eliminating the necessity of vacuum in forming the images.

An object of the invention is to provide new and improved thermoplastic recording not requiring the use of vacuum.

Another object of the invention is to provide new and improved thermoplastic recording films.

Another object of the invention is to provide new and improved thermoplastic recording methods and apparatus not requiring vacuum.

Another object of the invention is to provide methods and apparatus for forming a film having a groove image by forming charges on opposite sides of a transparent film by projecting light against one side of the film with a light sensitive chargeforming member on the other side of the film. The film with the charges then is heated to form grooves in at least one surface thereof and then is cooled to resolidify the film with the grooves therein.

A complete understanding of the invention may be obtained from the following detailed description of thermoplastic recording films, methods and apparatus forming specific embodiments thereof, when read in conjunction with the appended drawings, in which FIG. 1 is a perspective view of a thermoplastic recorder for practicing a method forming one embodiment of the invention;

FIG. 2 is an enlarged elevational of a portion of the thermoplastic recorder shown in FIG. 1;

FIG. 3 is an enlarged, fragmentary, vertical sectional view of the recorder of FIG. 1 illustrating the transfer of the charge pattern from a photoconductor drum to a film having a thermoplastic facing;

FIG. 4 is an enlarged, fragmentary, longitudinal sectional view of the film of FIG. 3;

FIG. 5 is a fragmentary sectional view of a thermoplastic recorder forming an alternate embodiment of the invention;

FIG. 6 is a fragmentary sectional view of a thermoplastic recorder forming another embodiment of the invention;

FIG. 7 is a fragmentary elevational view of a portion of the thermoplastic recorder shown in FIG. 6;

FIG. 8 is a fragmentary sectional view of a thermoplastic recorder forming another embodiment of the invention;

FIG. 9 is a fragmentary elevational view of the thermoplastic recorder shown in FIG. 8;

FIG. 10 is a fragmentary,'partially sectional view of a thermoplastic recorder forming a further embodiment of the invention; and

FIG. 11 is an enlarged fragmentary elevational view taken along line 11 11 ofFIG. 10.

The invention provides thermoplastic recording methods and apparatus in which a transparent film having a facing of thermoplastic material is positioned with the facing in contact with a charged photoconductive plate, and a light pattern is projected through the film to dissipate the charges on the plate in accordance with the light pattern. The charge pattern on the plate is then induced onto the facing, and the film is heated to soften the facing so that the charges thereon dimple the facing after which the film is cooled to solidify the dimpled facing. Images from the film may then be projected by a projector of the type described above and having gratings. In one method and apparatus embodying the invention, the film is advanced with a charged selenium drum and modulated line-like light beam is projected through a grating tape or film having a grating image thereon to the drum, the tape being advanced with the periphery of the drum so that the drum is discharged in spaced, modulated lines. A charge-transferring electrode roller than presses a film having a thermoplastic facing into contact with the drum to cause charges to form on opposite sides of the facing in the pattern in which the discharge was formed on the drum. In another embodiment of the invention, the drum is advanced intermittently past a fixed grating and images are projected in synchronism through the grating onto the drum to form the charge pattern on the drum. The grating may be a mask or may be formed optically by a prism having a grating pattern projected thereinto. In a further embodiment of the invention, the drum is advanced continuously and a modulated line on a cathode ray tube formed by horizontal scanning without vertical deflection is projected onto the drum to form spaced, modulated lines of discharged areas on the photoconductive drum, which may be effected without a grating or mask, the charge pattern being transferred to the facing on the film and the facing heated and cooled to form the dimples or lines as described above.

Referring now in detail to the drawings, there is shown in FIG. 1 a thermoplastic recorder having a light-tight housing I I in which a photoconductor drum 12 of a known type is rotated continuously. The drum has a photoconductor outer plate or layer 13 of selenium on an electroconductive layer 14. The photoconductor layer 13 is advanced past a known charge generator 15, which forms a positive charge on the surface of the photoconductor layer. The charge generator may be of the corona discharge type. After being charged, the layer 13 moves into proximity to but preferably out of contact with an endless tape or film 16 having a grating pattern thereon and a modulated, line-like light beam 17 is projected through linelike transparent portions to the surface of the photoconductor layer 13 to dissipate the charges thereon in accordance with the modulation of the light beam. Line-like opaque portions 16b separating the transparent lines 16a prevent dissipation of the charges on the portions of the layer 13 masked by the lines 16b. The modulation of the line-like light beam may be effected by a photographic film 18, for example, of the motion picture type, having images thereon, the film 18 being advanced continuously from a supply reel 19 to a take-up reel 20. A light source 21 projects light through an aperture plate 22 and a pressure plate 23 through a projector lens 24, which preferably has a relay lens therein for re-inverting the image and focusing the modulated line-like beam on the drum 12. The mask or grating 16 is endless and travels over pulleys or sprockets 25 and 26 which are parallel to shaft 27 of the drum 12 and hold the mask in contact with the periphery of the drum. The mask is entrained loosely over angularly disposed pulleys 28 and 29 which deflect the return portion of the mask out of the path of the light beam.

The photoconductor layer 13 having the charged pattern travels from the mask 16 to a charge-transferring electrode roller 41, which presses a thermoplastic recording film 42 into close contact with the charged layer 13. The film is supplied from a supply reel 39 through a light trapped opening in the housing 11. The film 42 has a thin, strong, transparent backing layer 42a of a high melting point dielectric material such as, for example, that sold under the trade name Mylar," and between the layer 42a and a thin, transparent thermoplastic facing 42b of a low melting point dielectric material such as,

for example, polyethylene there is a very thin, transparent layer 420 of electroconductive mat rial such as, for example, tin oxide. The electrode roller 41 is maintained at a potential relative to that of the initial charge on the layer 13 just below the threshold voltage necessary to transfer any charge from the undischarged lines or other undischarged portion on the layer 13 to the facing 4211. This voltage will be determined by the thickness of the film 42 as is well known in the electrophotography art. This voltage causes negative charges to form on the outer surface of the facing in strength inverse to facing portion of the positive charges of the charge pattern of the layer 13. This causes a pattern or image of negative charges to be formed on the outer surface of the facing 42b as the facing separates from the drum layer 13 as illustrated in FIG. 3. The intensity or strength of the charge at any point on the facing 42b is determined by the extent to which the oppositely facing portion of the layer 13 had been previously discharged which, in turn, was determined by the amount of light impinged thereon. Thus, the charge image on the facing 42b varies from no charge in the areas adjacent to the completely undischarged portions of the layer 13 and black portions of the image on the tape or film 18 through intermediate charges corresponding to any grays on the film 18 to completely transparent corresponding to transparent portions of the film 18.

The film 42 with the charge pattern thereon is advanced from the electrode roller 41 by a take-up reel 51 (FIG. 1) through a slot 11a in the housing and sequentially through a heater 52 and a cooling unit 53. The heater may be of the induction heating type to heat the thermoplastic facing 42b to the softened or near liquid state. The heater also may be of the infra-red ray type or other type suitable to provide the controlled heating to soften or melt the thermoplastic facing. The backing 42a has a substantially higher melting point than the facing 42b and is not softened appreciably during the heating. The opposite charges on opposite sides of the facing draw together in proportion to the strength of the charges to form grooves or dimples illustrated by grooves 42d, 42e, 42f and 42g (FIG. 4), the grooves 42d and 42f being deeper than the grooves 42e and 42g, the depth of the grooves being determined by the respective strengths of the charges. The deep grooves 42d and 42f will cause white in projection upon a white screen while the grooves 422 and 42g will cause grays to be formed in the projected image. Between the grooves 42d, 44e and 42f are ridges 42h which represent the areas covered by the opaque lines 16b of the mask 16 during formation of the charge pattern, and between the grooves 42f and 42g is shown an ungrooved plano portion 421' which in projection will cause black in the projected image, the plane portion not serving to refract the light so that it will be projected. The portions of the plane portion 42: correspond to black portions in the tape or film 18. The spacing between each pair of the grooves 42d, 42c and 42f is identical and the spacing between the grooves 42f and 42 is a multiple of that between the grooves 42d, 42c and 42f. A light 49 (FIG. 1) is provided to dissipate all charges on each portion of the layer 13 as that portion travels from the roller 41 to the charge generator 15.

The purpose of the grating pattern of the opaque lines 16b (FIG. 2) (which are shown exaggerated in width and spacing from one another for purposes of illustration) is to cause the ridges 42h (FIG. 4) to be formed to break up the areas which are to be projected from the film as lighted areas into a large number of refracting surfaces. With the large number of closely spaced refracting surfaces in a particular area of the film 42, during projection that area will refract the light to cause it to be formed into a light image on the screen. If the ridges 42h were not present, light areas on the film would all be depressed and the refracting portions of the areas would only be along the edges of the areas and the central portions of the areas would form black areas during projection.

A thermoplastic recorder 61 shown in FIG. is generally similar to that shown in FIG. 1 except that the recorder 61 operates cyclically rather than continuously. The recorder 61 includes a light source 62 projecting light through a shutter 63, an aperture plate 64, a film 65, an apertured pressure plate 66, a lens unit 67 including an erecting portion, and a stationary mask 68 to a photoconductor drum 69. The film 65 may be of the motion picture type and a known intermittent shuttle mechanism 70 operates in synchronism with the shutter to advance the film periodically, the drum 69 also being rotated in synchronism with the advancement of the film and the shutter 63 cutting off light while the film is advanced a frame and the drum is rotated one frame and then permitting the projection of light while the film 65 and drum 69 are stationary. The mask 68 has a grating-like pattern like that of the mask 16 to form dark lines across the film. This forms a charge pattern on the drum 69 which is identical with the drum 12 except for being intermittently or cyclically rotated. This charge pattern or image is transferred to thermoplastic recorder tape by means (not shown) like the electrode roller 41 but operated in synchronism with the drum 69.

A thermoplastic recorder 81 (FIGS. 6 and 7) is generally similar to the recorder 61 (FIG. 5) but in place of the mask 68 there is provided a prism type masking system 82. The masking system 82 includes a light source 83, a reticle 84 and a prism member 85 having a semi-transparent, semi-reflecting surface 86. An image to be recorded is projected optically by suitable known means such as, for example, a light source 87 and an objective 88 having an erecting or relay portion and images from a film 88 are formed on drum 89 identical with drum 69, the rays from the objective 88 traveling through the prism structure with the bright lines from the grating pattern superimposed on the image. The grating pattern in each of the recorders limits the width of the grooves formed in the thermoplastic facing 42 (FIG. 4). The bright lines from the grating pattern entirely dissipate the charge along lines across the drum 89. The film 88 is a negative and the pattern or modulated lines of light formed on photoconductor surface of the drum 89 from the film 88 is negative relative to those described above in connection with the recorders shown in FIGS. 1 and 5. That is, where a portion of the final image projected from thermoplastic recorder film 90 is to be white in projection no light is projected on to the drum from that corresponding portion of the film 88. Thus, on the drum there are completely discharged lines alternating with lines which according to the image from the film 88 are discharged in portions, partially discharged in other portions and fully charged in the remaining portions.

The transfer of the charge pattern from the drum 89 to a thermoplastic recorder film 90 (FIG. 7) by an electrode roller 91 identical with the roller 41 but which is maintained as is well understood in the xerographic art at a negative potential relative to the drum 89. The voltage between the negative potential of the electrode roller 91 and the discharged portions of the drum 89 is just at or slightly less than the threshold voltage necessary to induce a charge on the portions of the facing 90b in contact with the fully discharged portions of the drum 89. However, wherever the charges on the drum are undissipated a charge is induced on the facing portion of the facing 90b and the strength of the induced charge is in proportion to the strength of the charge on the oppositely facing portion of the drum. Thus, a charge pattern is induced on the facing in which there are no charges on completely discharged portions of the facing which are to be dark during subsequent projection, and the charges on the other portions of the facing are proportional to the amount of light to be transmitted in the image to be formed, thus covering the gray scale.

An electroconductive, charge-retaining shoe 92 which has a knife edge 92a urged into contact with the roller and the film 90 by spring 93 bearing on insulating pad 94 and tab 92b of the shoe, insulating guides 95 serving to guide the shoe. With the shoe contacting the film 90 as the film leaves the roller 91, the charge pattern on the film is retained even without any metallic or other electroconductive layer in the film 90. The shoe 92 extends out of housing 96 and through heating unit 97 which heats the film 90 sufficiently that grooved pattern 90a is formed in thermoplastic facing 90b of polyethylene or other suitable material of substantially lower melting point than that of backing 900. The film 90 travels from the heating unit 97 into and through a cooling unit 98 of a known type which solidifies the softened facing 90b, the shoe 92 extending thereinto to retain the charges in full strength until the facing has been rehardened.

A thermoplastic recorder 101 (FIGS. 8 and 9) is similar to that of FIG. 1 and has a continuously rotated photoconductor drum 102 identical with the drum 12 (FIG. 1). The charge pattern or image is formed on photoconductor layer 103 by a cathode ray tube 104 of a known type which has a horizontally scanned beam modulated to form an interrupted line image on screen 104a, there being no vertical deflection of the beam and the electron beam being stopped during flyback. The image formed on the screen 104a is imaged by an optical objective 105 which need not include an erecting or relay portion for reinverting the image, the necessity for erecting or handing being obviated by the direction of scanning of the electron beam. The recorder 101 also includes a charge transferring system in which a charge retaining electroconductive belt 106 contacts electrode roller 107 and travels in face-toface contact with recorder film 108 through light seal 109 in housing 110, heating unit 11 and cooling unit 112. The film 108 is of the same construction as the film 90 (FIG. 7). The belt 106 preferably is endless and is maintained at the same potential as the roller 107, being mounted on insulated rollers or pulleys (not shown), and keeps the high charge pattern on the film 108 until the grooves or dimples are formed and set.

In a thermoplastic recorder 121 (FIGS. and 11) light is projected from a light source 122 of known construction through a line-like aperture 123a in aperture plate 123, a film or tape 124 having images or patterns thereon of varying transparency, a pressure plate 125 and an optical objective 129 and is brought to a focus at mask 126. A relay lens 127 erects the image at the mask 126 and brings it into a line extending across photoconductor drum 128. The drum 128 and the film 124 are moved continuously and at synchronized speeds. The apertures 123a extends laterally or width-wise across the film 124 as does the modulated line of light on the drum 128 extend across the drum. The mask 126 has fully transparent lines 126a separated by opaque lines 126b, both of which lines 126a and 1263b extend normally to the line of modulated light so that dark lines from the lines 126b are formed on the periphery drum extending along the periphery rather than across the periphery. Thus, the lines 126b cause slight interruptions in the modulated lines of light projected onto the drum to form a raster or charge pattern. The charge pattern on the drum is utilized to form a charge pattern on a film (not shown) in a manner similar to that described above in connection with the recorder of FIG. l but with the ridges and modulated depressions extending longitudinally of the film rather than across the film. For projecting the film so produced by the recorder 122, the gratings of the projector are disposed so that the slots therein extend parallel to the length of the film and to pass refracted light from the dimples or grooves, which extend longitudinally of the film.

While the recorder 121 has been described as advancing both the film 124 and the drum 128 continuously with a line of light extending across the drum and the opaque lines 1261) extending longitudinally of the drum, the film 124 and the drum may be moved frame by frame with a shutter. Also, if desired, in the latter instance the mask 126 may be turned 90 so that the opaque lines 1261: extend parallel to the axis of rotation of the drum rather than parallel to or longitudinally of the periphery of the drum.

While the invention is thus described, it is not wished to be limited to the precise details described, as changes may be readily made without departing from the spirit of the invention.

What is claimed is:

l. A method of recording information on a dielectric thermoplastic material in the form of a ripple pattern comprising placing a uniform electrostatic charge on one surface of a layer of dielectric photoconductive material, bonding said one surface to a layer of thermoplastic material, light modulating said photoconductive layer to form a charge pattern on said one surface thereof in accordance with the information to be recorded, transferring said charge pattern to said thermoplastic layer to form a corresponding electrostatic force pattern therein, heating said thermoplastic layer to its melting point to form therein a ripple pattern corresponding to said force pattern, and cooling said thermoplastic layer to fix said ripple pattern.

2. The method as defined in claim 1 in which said photoconductive layer is light modulated to form said charge pattern in the form of spaced lines.

3. The method as defined in claim 1 in which said photoconductive layer is light modulated to form said charge pattern in parallel line form and said charge pattern is transferred to said thermoplastic layer by bringing said thermoplastic layer into intimate proximity with said one surface to induce charges corresponding to said charge pattern on said thermoplastic layer and applying an electric field to the charges on said thermoplastic layer.

4. The method as defined in claim 1 in which said dielectric photoconductive material is in the form'of a continuous coating on the surface of a rotated drum, one facing of said thermoplastic layer is held in engagement with said continuous coating, and said charge pattern is transferred to said thermoplastic layer by creating a voltage between the side of said thermoplastic layer remote from said facing and said drum surface of a charge transferring magnitude to charge said facing in accordance with the charge pattern on said coating.

5. The method as defined in claim 4 in which said charge pattern is created by projecting light from a light source through lens means and through a film positioned between said light source and said lens means and through a grating between said light source and said layer of photoconductive material.

6. The method as defined in claim 5 in which said grating and said photoconductive layer are moved in synchronization.

7. The method as defined in claim 5 in which said grating is secured in a fixed position and said photoconductive layer is moved intermittently past said grating.

8. The method defined in claim 5 in which said grating comprises mask means for creating dark lines in the image projected onto said photoconductive material.

9. The method as defined in claim 1 in which said layer of photoconductive material is formed as a continuous peripheral surface of a rotated drum, said photoconductive layer is light modulated by projecting images successively onto said surface in synchronization with the rotation of said drum, said layer of thermoplastic material is held in contact with a portion of said surface with electrode means during transfer of said charge pattern, and said thermoplastic layer is drawn from said surface while maintaining the charge pattern on said thermoplastic layer.

10. The method as defined in claim 1 in which said layer of photoconductive material is formed as a continuous surface of an intermittently rotated drum, said photoconductive surface is light modulated by intermittently advancing film containing a pattern to be duplicated and intermittently projecting light through said film onto said drum surface to create said charge pattern, said charge pattern is transferred by advancing said thermoplastic layer into contact with said drum surface, holding said thermoplastic layer against said drum surface and creating a charge-forming voltage across said thermoplastic layer, and including the step of retaining said charge pattern while heating and cooling said thermoplastic layer.

11. The method as defined in claim 1 in which said layer of said photoconductive material is formed as a continuous peripheral surface of a rotating drum, said uniform electrostatic charge is placed at a first point along the path of said peripheral surface, said peripheral surface is light modulated at a second point along the path thereof to form said charge pattern, and said charge pattern is transferred to said thermoplastic layer by guiding a facing of said thermoplastic layer into contact with a portion of said peripheral surface having said charge pattern, contacting said thermoplastic layer at a third point along the path of said peripheral surface with a charge transferring electrode and applying an electric field to the charge pattern through said electrode to induce changes on said facing in accordance with the charge pattern on said peripheral surface.

12. The method as defined in claim 1 in which said photoconductive surface bearing said charge is moved in a predetermined direction, said charge pattern is transferred by contacting said photoconductive surface bearing said charge pattern with said thermoplastic layer and placing electrode means at a charge transferring potential relative to said surface adjacent said point of contact to form said charge pattern on said layer, and said thermoplastic layer is heated by advancing said layer through a heating unit while said layer and said electrode means are in contact with electroconductive means to maintain the strength of charge pattern on said layer in said heating unit.

13. Themethod as defined in claim 12 in which said electrode means and electroconductive means include an electrode roller and an electroconductive tape positioned between and in contact with said roller and the thermoplastic layer and movable with said thermoplastic layer through the heating unit.

14. The method as defined in claim 1 in which said photoconductive layer is formed as a continuous coating over a major surface portion of a rotatable drum, said drum is rotated relative to an electrostatic charging device and a light source, said charge is placed as a continuous uniform charge on said coating, and said thermoplastic layer is placed in engagement with said coating to transfer said charge pattern thereto.

15. The method as defined in claim 14 in which said transferring step includes applying a recharge voltage across said thermoplastic layer and coating while said thermoplastic layer and coating are in engagement thereby placing a higher charge on areas of said thermoplastic layer which are opposite said discharged areas than on other areas of said layer.

16. The method as defined in claim 1 in which said photoconductive layer is light modulated by projecting means to form said charge pattern in a line form, corresponding to predetermined information, said photoconductive surface and projecting means are relatively moved to form spaced lines of discharged areas on said photoconductive surface, and said charge pattern is transferred by placing the facing of said thermoplastic layer in contact with said photoconductive surface to create a charge pattern on said facing in accordance with the charge pattern on said photoconductive surface, and applying an electric field to the charge on the film.

17. The method as defined in claim 16 in which said modulated charge pattern corresponding to predetermined information is formed on said photoconductive surface subsequent to formation of said spaced lines of discharged areas.

18. In a thermoplastic recorder, a charged photoconductor surface, means for creating a charge pattern on the surface in the form of spaced, modulated lines, including a light source and lens means for imaging on the photoconductor surface a film positioned between said light source and the lens means and a grating between said light source and said photoconductor surface, said grating comprising mask means for creating dark lines in the image projected onto the photoconductor surface, said mask means including a reticle light source, prism means for combining the light from the reticle light source with the light of the pattern creating means, and a reticle between the prism means and the reticle light source for creating dark lines in the image on the photoconductor surface, means for placing a facing of a thermoplastic recorder film in contact with the surface to create a charge pattern on the facing in accordance with the charge pattern on the surface, means for applying an electric field to the charge on the film, and means for temporarily heating the film to dimple it in accordance with the charge thereon.

19. A recorder comprising a film, means for moving the film along a path, a member having a photoconductive surface spaced from the film, means for placing a charge on the surface, means for moving the member parallel to the path of the film, means for projecting light through the film and toward the photoconductive surface, objective lens means disposed to focus the light in a plane between the film and the photoconductive surface, relay lens means for focusing onto the surface light from the plane, and a mask having a plurality of laterally spaced opaque lines positioned in the plane. 

2. The method as defined in claim 1 in which said photoconductive layer is light modulated to form said charge pattern in the form of spaced lines.
 3. The method as defined in claim 1 in which said photoconductive layer is light Modulated to form said charge pattern in parallel line form and said charge pattern is transferred to said thermoplastic layer by bringing said thermoplastic layer into intimate proximity with said one surface to induce charges corresponding to said charge pattern on said thermoplastic layer and applying an electric field to the charges on said thermoplastic layer.
 4. The method as defined in claim 1 in which said dielectric photoconductive material is in the form of a continuous coating on the surface of a rotated drum, one facing of said thermoplastic layer is held in engagement with said continuous coating, and said charge pattern is transferred to said thermoplastic layer by creating a voltage between the side of said thermoplastic layer remote from said facing and said drum surface of a charge transferring magnitude to charge said facing in accordance with the charge pattern on said coating.
 5. The method as defined in claim 4 in which said charge pattern is created by projecting light from a light source through lens means and through a film positioned between said light source and said lens means and through a grating between said light source and said layer of photoconductive material.
 6. The method as defined in claim 5 in which said grating and said photoconductive layer are moved in synchronization.
 7. The method as defined in claim 5 in which said grating is secured in a fixed position and said photoconductive layer is moved intermittently past said grating.
 8. The method defined in claim 5 in which said grating comprises mask means for creating dark lines in the image projected onto said photoconductive material.
 9. The method as defined in claim 1 in which said layer of photoconductive material is formed as a continuous peripheral surface of a rotated drum, said photoconductive layer is light modulated by projecting images successively onto said surface in synchronization with the rotation of said drum, said layer of thermoplastic material is held in contact with a portion of said surface with electrode means during transfer of said charge pattern, and said thermoplastic layer is drawn from said surface while maintaining the charge pattern on said thermoplastic layer.
 10. The method as defined in claim 1 in which said layer of photoconductive material is formed as a continuous surface of an intermittently rotated drum, said photoconductive surface is light modulated by intermittently advancing film containing a pattern to be duplicated and intermittently projecting light through said film onto said drum surface to create said charge pattern, said charge pattern is transferred by advancing said thermoplastic layer into contact with said drum surface, holding said thermoplastic layer against said drum surface and creating a charge-forming voltage across said thermoplastic layer, and including the step of retaining said charge pattern while heating and cooling said thermoplastic layer.
 11. The method as defined in claim 1 in which said layer of said photoconductive material is formed as a continuous peripheral surface of a rotating drum, said uniform electrostatic charge is placed at a first point along the path of said peripheral surface, said peripheral surface is light modulated at a second point along the path thereof to form said charge pattern, and said charge pattern is transferred to said thermoplastic layer by guiding a facing of said thermoplastic layer into contact with a portion of said peripheral surface having said charge pattern, contacting said thermoplastic layer at a third point along the path of said peripheral surface with a charge transferring electrode and applying an electric field to the charge pattern through said electrode to induce changes on said facing in accordance with the charge pattern on said peripheral surface.
 12. The method as defined in claim 1 in which said photoconductive surface bearing said charge is moved in a predetermined direction, said charge pattern is transferred by contacting said photoconductivE surface bearing said charge pattern with said thermoplastic layer and placing electrode means at a charge transferring potential relative to said surface adjacent said point of contact to form said charge pattern on said layer, and said thermoplastic layer is heated by advancing said layer through a heating unit while said layer and said electrode means are in contact with electroconductive means to maintain the strength of charge pattern on said layer in said heating unit.
 13. The method as defined in claim 12 in which said electrode means and electroconductive means include an electrode roller and an electroconductive tape positioned between and in contact with said roller and the thermoplastic layer and movable with said thermoplastic layer through the heating unit.
 14. The method as defined in claim 1 in which said photoconductive layer is formed as a continuous coating over a major surface portion of a rotatable drum, said drum is rotated relative to an electrostatic charging device and a light source, said charge is placed as a continuous uniform charge on said coating, and said thermoplastic layer is placed in engagement with said coating to transfer said charge pattern thereto.
 15. The method as defined in claim 14 in which said transferring step includes applying a recharge voltage across said thermoplastic layer and coating while said thermoplastic layer and coating are in engagement thereby placing a higher charge on areas of said thermoplastic layer which are opposite said discharged areas than on other areas of said layer.
 16. The method as defined in claim 1 in which said photoconductive layer is light modulated by projecting means to form said charge pattern in a line form, corresponding to predetermined information, said photoconductive surface and projecting means are relatively moved to form spaced lines of discharged areas on said photoconductive surface, and said charge pattern is transferred by placing the facing of said thermoplastic layer in contact with said photoconductive surface to create a charge pattern on said facing in accordance with the charge pattern on said photoconductive surface, and applying an electric field to the charge on the film.
 17. The method as defined in claim 16 in which said modulated charge pattern corresponding to predetermined information is formed on said photoconductive surface subsequent to formation of said spaced lines of discharged areas.
 18. In a thermoplastic recorder, a charged photoconductor surface, means for creating a charge pattern on the surface in the form of spaced, modulated lines, including a light source and lens means for imaging on the photoconductor surface a film positioned between said light source and the lens means and a grating between said light source and said photoconductor surface, said grating comprising mask means for creating dark lines in the image projected onto the photoconductor surface, said mask means including a reticle light source, prism means for combining the light from the reticle light source with the light of the pattern creating means, and a reticle between the prism means and the reticle light source for creating dark lines in the image on the photoconductor surface, means for placing a facing of a thermoplastic recorder film in contact with the surface to create a charge pattern on the facing in accordance with the charge pattern on the surface, means for applying an electric field to the charge on the film, and means for temporarily heating the film to dimple it in accordance with the charge thereon.
 19. A recorder comprising a film, means for moving the film along a path, a member having a photoconductive surface spaced from the film, means for placing a charge on the surface, means for moving the member parallel to the path of the film, means for projecting light through the film and toward the photoconductive surface, objective lens means disposed to focus the light in a plane between the film and the photoconductive surface, relay lens means foR focusing onto the surface light from the plane, and a mask having a plurality of laterally spaced opaque lines positioned in the plane. 